1. Field of the Invention
The invention relates generally to heavy-duty wheeled vehicles. More particularly, the invention is directed to frames and subframes for semi-trailers. Even more specifically, the invention is directed to a mud flap mounting assembly that is pivotally attached to the frame of a semi-trailer. The mud flap assembly is lightweight, easy to assemble, and prevents damage to the mud flap, the mud flap angle bracket and the mud flap bracket. The mud flap assembly also prevents damage to cross members or other structural components to which the mud flap assembly is connected when the mud flap is pinched between a tire and a fixed curb during operation of the heavy-duty vehicle. The mud flap assembly is relatively easy to assemble during installation of the subframe onto the heavy-duty vehicle.
2. Background Art
Heavy-duty wheeled vehicles, such as tractor-trailers or semi-trailers, typically include one or more suspension assemblies that connect the wheel-bearing axles of the vehicle to the frame of the vehicle. In some heavy-duty vehicles, the suspension assemblies are connected directly to the primary frame of the vehicle. In other heavy-duty vehicles, the primary frame of the vehicle supports a subframe, and the suspension assemblies connect directly to the subframe. Subframes have been utilized on tractor-trailers for many years. The subframe is a box-like structure that is mounted on the underside of the trailer body of the tractor-trailer and one or more axle/suspension systems are suspended from the subframe structure. For those heavy-duty vehicles that support a subframe, the subframe can be non-movable or movable, the latter being commonly referred to as a slider box, slider subframe, slider undercarriage, or secondary slider frame. A trailer having a slider box gains an advantage with respect to laws governing maximum axle loads. Proper placement of the slider box varies individual axle loads or redistributes the trailer loads so that it is within legal limits. Once properly positioned, the slider box is locked in place on the underside of the trailer by a retractable pin mechanism. For the purpose of convenience and clarity, reference herein will be made to slider boxes, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicles having main members, such as primary frames, movable subframes and non-movable subframes, and also applies to heavy-duty vehicles that do not have main members or subframes.
The axle/suspension system is typically suspended from the main members of the slider box by a pair of aligned and spaced-apart depending hangers. More specifically, each suspension assembly of an axle/suspension system includes a longitudinally extending elongated beam. Each beam typically is located adjacent to and below a respective one of a pair of spaced-apart longitudinally extending main members and one or more cross members, which form the slider box of the vehicle. Each beam is pivotally connected at one of its ends to a hanger, which in turn is attached to and depends from a respective one of the main members of the slider box of the vehicle. An axle extends transversely between and typically is connected by some means to the beams of the pair of suspension assemblies at a selected location from about the mid-point of each beam to the end of the beam opposite from its pivotal connection end. The opposite end of each beam also is connected to a bellows air spring or its equivalent, which in turn is connected to a respective one of the main members.
Typically, in a slider box configuration, mud guards or mud flaps are suspended from a mud flap mounting bracket that spans the width of the slider box and that is attached to the main members of the slider box at a fixed distance rearward of the tires. A mud flap angle bracket is in turn mounted on the mud flap bracket and spans the entire width of the semi-trailer. The mud flaps are mounted on the mud flap angle bracket via heavy bolts disposed through aligned openings formed in the mud flaps and the mud flap angle bracket. Each mud guard or mud flap is spaced sufficiently behind the tires to minimize the likelihood of the mud flap rubbing the tires or getting caught in the tires, yet close enough to the tires to deflect the greatest amount of dirt, debris and/or water cast off of the tires during operation of the vehicle.
These prior art mud flap mounting brackets and angle brackets are prone to deformation and/or potential failure when the mud flap is pinched between the tires of the vehicle and a curb or other fixed object, such as when the vehicle is backing up into a loading dock or a parking space that includes a curb or other fixed object such as a railroad tie. More particularly, in this situation, the mud flap is pinched between the tires and the curb or other fixed object and the mud flap is pulled downwardly resulting in deformation of the mud flap mounting bracket and/or the mud flap angle bracket, and additionally may cause tearing of the mud flap away from the mounting bolts attaching the mud flap to the mud flap angle bracket. As a result, the mud flap mounting bracket and the mud flap angle bracket, as well as the mounting bolts, must be sufficiently robust to minimize or reduce deformation when the mud flap is pinched between the tires and a curb or other fixed object. This increases the weight of the slider box and in turn reduces the amount of cargo that can be carried by the vehicle.
Other types of mud flap mounting brackets also exist and are most commonly seen on heavy-duty trucks. These mud flap mounting brackets typically attach to the truck frame and project outboardly from the truck frame. A mud flap is secured to the bracket behind the tires of the truck. These types of mud flap mounting brackets typically include a spring within the outboardly projecting bracket that is attached at one end to the bracket and at the other end to the truck frame. This configuration allows the bracket to pivot at the bracket-to-truck frame interface, thereby allowing the outboard end of the bracket to pivot downwardly or in other directions, but the bracket-to-truck frame interface remains at the original height. This configuration eliminates problems associated with deformation of the bracket but does not resolve the problem of the mud flap tearing from the mounting bolts, potentially causing damage to the mud flap.
Therefore, a need exists in the art for a mud flap mounting assembly that is relatively lightweight, provides for easy assembly of the mud flap mounting assembly and which overcomes the problems of the prior art mud flap mounting brackets set forth above. The mud flap mounting assembly of the present invention overcomes the problems associated with prior art mud flap mounting brackets by providing a mud flap mounting assembly for a slider box of a semi-trailer that is relatively lightweight, easy to assemble and that provides generally parallel deflection or downward rotation of the mud flap and the mud flap mounting bracket with respect to the ground thereby eliminating deformation and damage to the mud flap bracket and also eliminating tearing away of the mud flap from the mounting bracket when the mud flap is pinched between the tires and a curb or other fixed object.